<fix>[kvm]: add null check for dstHostUuid in secure boot

Add a null check for dstHostUuid before querying TPM info
in KvmSecureBootExtensions to prevent NullPointerException
when destination host is not specified.

Resolves: ZSV-11731
Related: ZSV-11310

Change-Id: I75706a697969776f617667686864617376717274

Author: Zhang Wenhao

plugin/kvm/src/main/java/org/zstack/kvm/efi/KvmSecureBootExtensions.java

@@ -168,6 +168,11 @@ public void preVmMigration(VmInstanceInventory vm, VmMigrationType type, String
             return;
         }
 
+        if (dstHostUuid == null) {
+            completion.success();
+            return;
+        }
+
         String tpmUuid = Q.New(TpmVO.class)
                 .eq(TpmVO_.vmInstanceUuid, vm.getUuid())
                 .select(TpmVO_.uuid)